In a known prior art device of this class (DE 31 51 151 C2), both a sonotrode and an anvil are rotatably journalled, each about their own longitudinal axis. These axes are perpendicular to each other and are spaced apart, in order that the various sonotrode projections and the corresponding anvil recesses can be adjusted relative to one another for forming different compaction spaces. Only one compaction space can be formed each time, with the result being that only one conductor end weld can be performed in each operation. If conductor ends of different cross-sectional dimensions are to be compacted and welded, then the sonotrode and the anvil must be reset relative to each other on each occasion.
An arrangement is already known in the prior art (DE 31 51 151 C2, FIGS. 3 and 4), by which two conductors can be welded simultaneously in different compaction spaces in one operation. However, for this purpose two separate anvils must be associated with a sonotrode rotatable about its longitudinal axis. These anvils are each rotatably journalled about their own longitudinal axis, with the result being that the device not only becomes larger and more expensive, but also allows for the simultaneous welding of only those types of welds which can be carried out on adjacent sonotrode surfaces on one sonotrode projection.